CHEMICAL RELATIONS OF NUCLEUS AND CYTOPLASM 241 



the nuclein may be synthetically formed by the re-combination of 

 these two substances. Pure nucleic acid contains no sulphur, a 

 high percentage of phosphorus (above 9 %), and no albumin. By 

 adding it to a solution of albumin a precipitate is formed which 

 contains sulphur, a lower percentage of phosphorus, and has the 

 chemical characters of nuclein. This indicates that the discord- 

 ant results in the analyses of nuclein, referred to above, were 

 probably due to varying proportions of the two constituents ; and 

 Altmann suggested that the "nuclein" of spermatozoa, which con- 

 tains no sulphur and a maximum of phosphorus (over 9.5 %), might 

 be uncombined nucleic acid itself. Kossel accordingly drew the 

 conclusion, based on his own work as well as that of Liebermann, 

 Altmann, Malfatti, and others, that " what the histologists designate 

 as chromatin consists essentially of combinations of nucleic acid with 

 more or less albumin, and in some cases may even be free nucleic 

 acid. The less the percentage of albumin in these compounds, the 

 nearer do their properties approach those of pure nucleic acid, and 

 we may assume that the percentage of albumin in the chromatin 

 of the same nucleus may vary according to physiological condi- 

 tions." 1 In the same year Halliburton, following in part Hoppe- 

 Seyler, stated the same view as follows. The so-called " nucleins " 

 form a series leading downward from nucleic acid thus : - 



(1) Those containing no albumin and a maximum (910 %) of phos- 



phorus (pure nucleic acid). Nuclei of spermatozoa. 



(2) Those containing little albumin and rich in phosphorus. Chro- 



matin of ordinary nuclei. 



(3) Those with a greater proportion of albumin a series of sub- 



stances in which may probably be included pyrenin (nucleoli) 

 and plastin (linin). These graduate into 



(4) Those containing a minimum (0.5 to I %) of phosphorus 



the nucleo-albumins, which occur both in the nucleus and in 

 the cytoplasm (vitellin, caseinogin, etc.). 



Finally, we reach the globulins and albumins, especially character- 

 istic of the cell-substance, and containing no nucleic acid. " We thus 

 pass by a gradual transition (from the nucleo-albumins) to the other 

 proteid constituents of the cell, the cell-globulins, which contain no 

 phosphorus whatever, and to the products of cell-activity, such as 

 the proteids of serum and of egg-white, which are also principally 

 phosphorus-free." 2 Further, " in the processes of vital activity there 

 are changing relations between the phosphorized constituents of the 

 nucleus, just as in all metabolic processes there is a continual inter- 



1 '93, P- i5 8 - * '93, P- 574- 



u 



